Author(s)

F. Seiler, G. Mathieu & H. Peter

Abstract

Extreme heat flux is transferred during gun tube firing from the hot propelling gases into the barrel of the powder gun. Some well known methods can be used to reduce the gun tube heating, e.g. by adding special materials into the propellant or by placing them at the back side of the projectile fired. A very familiar additive is the Swedish additive, which is a combination of Titanium dioxide particles (TiO2) and wax. Other additive particles are for example calcium carbonate (CaCO3), Aerosil (SiO2) and others. It is supported by several studies that the additive particles form a thin deposit layer on the barrel’s inner surface with a thickness of some micrometers per firing, thus protecting the inner surface of the gun barrel. For estimating the heating of the barrel in the case where an additive layer is present, a boundary layer model combined with the heat conduction equation was applied for calculating the bore temperature, especially at the interface between the additive and gun barrel. The aim is to lessen as much as possible the interface temperature by additive adding. The heat flux formation depends mainly, for a specified gun weapon, on the thickness a of the additive layer as well as on the physical properties of the additive applied, i.e., the density ρ, the specific heat c and the heat conductivity λ. These parameters have been varied in a wide range in order to find out those additive properties for which the heating of the gun barrel is most efficiently lessened. 1 Introduction Unfortunately the mechanism behind the protective action of additive particles has not been fully understood until now. There are several theories trying to explain the action of additives on erosion reduction in gun barrels. One of them deals with heat transfer reduction by forming a thin additive layer of some

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